Hi Guys,
Just thought I would put my two pennith in.... I'm also fairly new to the robot world, built my first one (HW) last year for Robot Wars ... Anyway, I then decided to build a FW, but to be honest had I known in the first place what I know now (now there's an old saying...) I would have gone for the beetleweight - which I have just completed. I feel it's a great starting point, plenty of different materials, motors etc out there and plenty of scope for weapon and protection @ 1.5kg. Also found that cost wise, not mega expensive, infact keep it simple and the final outlay could be less than £50 for the robot, shop around for secondhand and might even get radio gear thrown in too. Finally, I have found that from FW down to Ant weight - transportation to events is easy, and work space required is minimal.
Hope this helps and please remember this is only my opinion. Good luck.